Liquid phase reforming process



Nov. 12, 1968 w. F. TAYLOR LIQUID PHASE REFORMING PROCESS Filed March 2,1967 D E F. F O 2 H REACTOR PRODUCT GAS SEPARATOR.

FIG.

GAS

GAS

GAS

LIQUID FIG. 2

W. F. TAYLOR INVENTOR PATENT ATTORNEY United States Patent 3,410,661LIQUID PHASE REFORMING PROCESS William F. Taylor, Scotch Plains, N..I.,assignor to Esso Research and Engineering Company, a corporation ofDelaware Continuation-impart of application Ser. No. 385,931,

July 29, 1964. This application Mar. 2, 1967, Ser.

4 Claims. (Cl. 23-213) ABSTRACT OF THE DISCLOSURE A hydrogen gas productis produced by reaction of liquid hydrocarbons with water in thepresence of a nickel reforming catalyst at low reaction temperatures,e.g., 110 to 500 F., and at atmospheric pressure and above.

CROSS REFERENCES This application is a continuation-in-part of Ser. No.385,931, filed July 29, 1964, now abandoned, by William F. Taylor onproducing gas rich in hydrogen from hydrocarbons contacted with water inliquid phase with a catalyst as herein described and claimed rather thanfrom hydrocarbons in vapor phase at low pressures and low temperatures.

The liquid phase reforming of hydrocarbons with water in the presence ofa solid catalyst for producing a gas product rich in hydrogen is adistinctly novel achievement. In contrast to vapor phase reforming, theliquid phase reforming conserves large quantities of heat needed forvaporization in vapor phase reforming and thus improves the thermalefficiency of the process.

BACKGROUND The reaction of gaseous hydrocarbons, e.g., methane to butaneor vaporized normally liquid hydrocarbons, e.g., naphtha, with steam atabove 500 C. (932 F.) in the presence of a catalyst to form hydrogen,methane and carbon oxides as principal product is well known as asteam-reforming process.

In steam-reforming of gaseous or vaporized hydrocarbons, high reactiontemperatures favor hydrogen production relative to methane, andcatalysts with sufiicient activity to insure high conversion rates areknown to have been used to make such a reaction go to completion attemperatures above 1000 F.

It is also known that a gas rich in hydrogen can be produced at lowertemperatures in the range of 550 to 950 F. by reaction of vaporizedhydrocarbons with steam at elevated pressures of 150 to 1500 p.s.i.a.when the conversion level is below 40%, i.e., with shortened time ofcontact in the presence of highly active catalysts to prevent increasedformation of methane, such as results from the methanation reaction ofhydrogen with carbon monoxide as reaction is extended to approachequilibrium.

SUMMARY OF THE INVENTION The liquid phase reforming process consists incontacting a nickel catalyst of high reforming activity with a liquidfeed mixture of hydrocarbon oil and water at low temperatures,preferably in the range of 110 to 500 F. and by obtaining a separationof hydrogen-rich product as it is formed, thus achieving essentially adifferential reaction, i.e., a reaction operating at low hydrocarbonconversion in which the production of hydrogen is enhanced relative tomethane. A gas collection zone free of catalyst is maintained contiguousto a bed of the catalyst flooded by the liquid reaction mixture toobtain a rapid separation of the gas from the catalyst. The liquidreaction 3,410,661 Patented Nov. 12, 1968 mixture feed is preferably inthe form of an oil-in-water emulsion.

Up until now there has been no teaching in the prior art on reforming ofaqueous emulsions of hydrocarbons to produce hydrogen or gas productsrich in hydrogen.

In the previously known vapor phase reforming processes, the water andhydrocarbon feeds have to be vaporized and heated to an elevatedtemperature for supplying the endothermic heat of reaction. Theincreased contact of the gas products with the catalyst increases theconversion of hydrocarbon and favors the formation of methane. The heatrequired for vaporizing and superheating the vapors is of a highmagnitude and costly. A subsequent processing of the gas products forseparation of components requires extensive cooling and more operations.

The production of hydrogen by reforming hydrocarbons at ultra lowtemperatures with nearly negligible formation of 'CO and CH was notpossible without a catalyst of high activity and without a method forminimizing contact of the gas products with the catalyst under the lowtemperature conditions which theoretically favor formation of mehaneraher than hydrogen.

Advantageously, by the use of low temperatures and sufficient pressureto maintain the hydrocarbon and water principally in the liquid phase,the partial or differential conversion permits the use of highly activereforming catalyst which almost at the instant of contact with the feedforms principally hydrogen and very little normally gaseoushydrocarbons, e.g., methane, ethane, propane, and butane. Also, in usinglow reaction temperatures, the catalyst life is prolonged because thereis less danger of oxidation, sintering, or coking.

Highly active catalysts useful for the low temperature partialconversion of the hydrocarbons to obtain principally hydrogen aretypified by mixed nickel-alumina and nickel-silica catalysts which havenickel contents from 10 to wt. percent, preferably 40 to 45 wt. percentand these mixed catalysts may be promoted by certain metals, e.g.,barium, strontium, cesium, cerium, lanthanum, yttrium, iron, potassium,and copper, present as oxides, carbonates, or both oxides andcarbonates. The proportion of promoter may be between 0.5 to 12 wt.percent of the catalyst.

Since highly active catalysts per se and methods for making them areregarded as known in the prior art, details on all such catalysts arenot set forth, but general characterizations and representative examplesare given.

In general, the highly active nickel catalysts have high nickel surfaceareas, i.e., 20 to 30 m. g. They are obtained by coprecipitations ofnickel with aluminum as hydroxides, carbonates, or basic carbonates fromaqueous solutions of nitrate salts by use of NH HCO at low temperature(200 to 400 F drying of the precipitates, and low temperature (400 to900 F.) calcining of the dried precipitates in air and low temperature(600 to 900 F.) activation of the calcined precipitates by hydrogen. Thepromoters are admixed as decomposable compounds, e.g., hydroxides,carbonates or nitrates with the precipitates. Similarly mixed catalystsof nickel with silica may be prepared using a metasilicate andkieselguhr, in place of aluminum compounds to have the nickelinterspersed with SiO instead of A1 0 The catalyst granules may be 1 to5 mm. particles or be compressed into pellets or be extruded.

As specific examples of catalysts which may be used in the practice ofthis invention, there can be mentioned: ceria promoted nickel-aluminacatalysts, lanthanum promoted nickel-alumina catalysts andcerium-lanthanum promoted nickel-alumina catalysts made in accordancewith the procedure set forth in copending commonly assigned applicationS.N. 317,777; catalytic metals of Group VIII deposited as hydrosilicateson a porous solid support as set forth in commonly assigned copendingapplication S.N. 317,828; now.U.S. Patent No. 3,351,566; potassium,cesium, barium and strontium promoted Ni-Al O made in accordance withthe procedure set forth in the copending commonly assigned applicationS.N. 317,799; now US. Patent No. 3,320,182; Ni-Al O -Fe made inaccordance with the procedure set forth in copending commonly assignedapplication S.N. 317,800; and Ni- ZnCrO -Al O -Ba made in accordancewith the procedure set forth in copending commonly assigned applicationS.N. 365,803, and promoted nickel-alumina catalysts made in accordancewith the procedure set forth in copending commonly assigned applicationS.N. 365,566. Higher nickel content promoted mixed Ni-Al O catalysts arealso highly active for the low temperature partial conversion ofhydrocarbons to hydrogen. These catalysts have nickel to aluminum atomratios usually in the range of 1.5/1 to 4/1 and can be promoted byelements from the group consisting of La, Ba, Sr, Ce, Cs, K, Fe, Y andCu.

Hydrocarbons which can be used as a feed in producing hydrogen includethe paraffinic hydrocarbons, saturated, unsaturated and cyclic,preferably straight chain saturated hydrocarbons having from 5 to 20carbon atoms depending on the mode of operation. Examples ofhydrocarbons which can be present in the feed include pentane, hexane,heptane, octane, decane, dodecane, heptene, and pentene. Thehydrocarbons to be used as feed mixed with water in an oil/wateremulsion are mainly those of higher boiling points, e.g., above 200 F.The hydrocarbon oil feed may include some partially oxygenatedhydrocarbons, e. g., alcohols, aldehydes, ketones, esters and ethers,preferably such compounds that have partial miscibility with the Water.Generally, the ratio of Water to hydrocarbon is in the range of fromabout 0.5 to 1, to 6 to 1 gram moles of water per gram atom of carbon,but higher proportions of water aid in forming more stable emulsions.

From analyses of products, proportions of reactants, and otherconsiderations, the partial conversion yielding 'high amounts ofhydrogen may be regarded as involving the following overall principalreaction paths, assuming that n-hexane is typical of the averagehydrocarbon reactant:

Reaction (1) implies that the hydrocarbon initially decomposes in thepresence of H 0 to liberate hydrogen and form an oxide of carbon,presumably carbon monoxide. Following this, the carbon monoxide reactsrapidly with water to form carbon dioxide and more hydrogen in the WaterGas Shift reaction (2). The carbon monoxide may also react with hydrogento form methane and water in the methanation reaction (3). Thethermodynamic equilibrium for reactions (2) and (3) are known to controlthe product composition at complete hydrocarbon feed conversion.However, reaction (2) is very rapid relative to reaction (1) since theproduct contains very little carbon monoxide at low conversion levels.Reaction (3) is slow relative to reactions (1) and (2). This forms thetheoretical basis for this invention since it allows a hydrogen-richproduct to be formed at process conditions, where in terms ofequilibrium alone, a hydrogen-poor product would be expected, i.e., atlow temperature. This invention, moreover, is based on the unexpectedresult that a hydrogen-rich product is obtained in a differentialreaction system (e.g., low conversion levels per pass) at lowtemperatures and is not contingent on the validity of the reaction pathsproposed. Reaction 1) is endothermic and reaction (2) slightlyexothermic. Reaction (3) is strongly exothermic and tends to increasethe temperature in the reaction zone.

In the process of producing hydrogen by liquid phase reforming, a numberof procedures can be employed. The

hydrocarbon and water feed can be passed over the catalysts at a partialconversion level and the effluent passed into a gas-liquid separatoroperating at low temperature Where unconverted liquid hydrocarbon andwater is separated from the product gas. Inasmuch as low conversion isan essential feature of this invention, the liquid reaction mixture,that is, the unconverted hydrocarbon and the water in liquid phase canbe fed sequentially into a number of catalyst zones with intermediateproduct separation or it can be recycled back to one or more of thezones. By combining the removal ofhydrogen and CO from the reactionzones and feeding the unconverted hydrocarbon into a number of differentreaction zones or by recycle of the unconverted hydrocarbon and water,fast conversion of the entering hydrocarbon feed can be obtained withvery low conversion to methane.

Alternatively, the hydrogen can be removed selectively from the reactionzones, that is, the catalyst zones or beds, by using diffusionmembranes. Suitable diffusion membranes include palladium,palladium-silver and porous tetrafluoroethylene membranes depending onthe temperature used. The porous tetrafluoroethylene membranes are madeby intimately mixing finely divided tetrafluoroethylene with eitherammonium oxalate or ammonium carbonate, pressing the mixture into thedesired shape and then gradually heating the pressed structure fromambient up to about 190 F. in order to decompose the ammonium compoundthereby providing a porous element consisting essentially oftetrafiuoroethylene. The catalyst bed or layer itself can be containedinside a diffusional membrane, or diffusional membranes can be locatedin an alternating series after a differential catalyst section. Adifferential catalyst section provides low conversion levels per pass.

When feeding the hydrocarbon and Water as a liquid emulsion, thereaction system should be such that the hydrogen-rich gas is allowed toseparate from the catalyst bed as quickly as possible after it isformed. This is accomplished by means of a gas separation Zonecontiguous to the catalyst bed which is maintained free of catalyst.

The liquid emulsion can be fed to a catalyst bed with a catalyst freevapor space above the bed such that the product gas rises through thecatalyst bed as it is formed and escapes into the vapor space before anyappreciable secondary reaction to methane can occur. Such a system canconsist of a tube or duct partially filled with the catalyst and withthe liquid being fed horizontally to the catalyst bed in a flow system,or the liquid feed can be fed batchwise to such a system with suflicientcontact time allowed between feed additions to insure the conversion ofthe hydrocarbon.

Another way the liquid feed system can be used is by means of a seriesof enclosed differential catalyst beds in which continuous separation ofthe product gas and liquid feed is not achieved but where gas separationzones spaced between the differential reactors allows the product toescape from the catalyst bed before excessive conversion of the hydrogento methane occurs. Also, the product hydrogen can be separated from theunconverted feed and other product gases by use of diffusion membranessuch as palladium, palladium-silver and porous tetrafiuoroethylenemembranes.

When the reacting mixture is a liquid emulsion, the temperature of thereaction is preferably maintained between about and 500 F. Higher thanatmospheric pressure can be used in the emulsion system withoutexcessive secondary reaction of the product hydrogen to methane. Forexample, the secondary reaction is minimized by use of shallow catalystbeds which allow the product gas to escape quickly or by use of a largernumber of differential reactors or reaction zones in series withintervening gas product separation zones. In this manner, high pressurehydrogen can be generated at high thermal efficiency since the feed isnot vaporized to a substantial extent and there is no need for gascompressors to supply the high pressure with their high operating energyrequirements. Higher pressures with the liquid feed system will alsoallow a higher operating temperature with a lower catalyst requirementthan would a lowtemperature, low-pressure operation, since the operatingtemperature is dictated to a great extent by the amount of feedhydrocarbon and water which must be held in the liquid phase, which is afunction of their partial pressures at a given temperature.

DESCRIPTION OF THE DRAWING FIG. 1 is a flow diagram of an apparatususeful for the production of hydrogen from a normally liquid hydrocarbonand water mixture; and

FIG. 2 is a schematic simplified system showing a series of reactors orreaction zones wherein the conversion of liquid hydrocarbons to ahydrogen-rich gas takes place.

Referring now to FIG. 1, there is shown a conduit 1 for the admission ofthe liquid hydrocarbon oil feed to the system, conduit 2 for admissionof liquid water feed, conduit 3, wherein the hydrocarbon and water feedsare mixed to form an emulsion which is passed into heat exchanger 4where the emulsion is warmed. The warmed emulsion may be passed througha heater 5, which supplies heat for the desired reaction temperature,then into the reactor 6.

Reactor 6 contains one or more catalyst beds, i.e., beds of activenickel-containing catalyst particles, or surfaces coated with catalystfor the reforming reaction.

The product gases from the reforming reaction are re moved from reactor6 by means of conduit 7 and are passed through heat exchanger 4 wherethe product gases and unconverted hydrocarbon and water are cooled byindirect heat exchange with the liquid emulsion feed. The product gasesand condensate are removed from heat exchanger 4 at a loweredtemperature and are passed to gas-liquid separator 9 by conduit 8.

The gas-liquid separator 9 permits removal of the product gases whichcomprise primarily H carbon dioxide, and some methane or hydrocarbon gasby way of conduit 10. The unreacted liquid hydrocarbon condensate formsan upper liquid phase which is withdrawn through conduit 11 fromseparator 9 for recycling to conduit 1. The lower phase of liquid watercollected in separator 9 is withdrawn through conduit 12 and recycled towater-feed conduit 2.

The product gases removed from the separator 9 by conduit may then beseparated into component parts by liquefaction and fractionation or theymay be used as they are removed from the separator. The gases rich inhydrogen may beused efiectively as a fuel for a fuel cell. Gaseoushydrocarbon components separated from the H product may be used as aheating fuel, e.g., to undergo combustion for heating the feedstockgoing into the reactor 6.

Various known solvent absorption or adsorption processes may be used toremove carbon dioxide and gaseous hydrocarbons from the hydrogen.

In the basic process carried out as shown in the flow diagram of FIG. 1,the principal features of the process are mixing of liquid hydrocarbonoil feed with water feed to form an aqueous emulsion under pressure,heating of the emulsion under pressure to the desired reactiontemperature while maintaining the hydrocarbon and water principally inthe liquid phase upon contact of the emulsion with the solid catalyst inthe reactor in a manner which permits the gas to be removed as it isformed with a partial conversion of the hydrocarbon, and passing theunreacted liquid hydrocarbon and water together with the gas productthrough a cooler 4 to a separator 9 where the gas product is separatedfrom unreacted liquids. Using the catalyst in a plurality of beds inreactor 6 each of the beds may be in a separate tube surrounded by aheating medium so that heat is imparted by indirect heat exchange fromthe heating medium to the emulsion flowing through the catalyst beds andthe gas formed in each of the beds is made to flow with unreactedemulsion out of the tubes in reactor 6 through conduit 7 to the heatexchanger 4 for cooling, then to the separator 9.

By feeding 16.5 moles of liquid heptane and 159 moles of liquid waterinto conduits 1 and 2 shown in FIG. 1, it is possible to obtain ahydrogen-rich gas product with 0.1 to 15% conversion of the liquidheptane per pass using a temperature of 350 F. and a pressure of atleast 1350 p.s.i.a. so that the gas product contains less than 10% Watervapor.

In FIG. 2 is shown a reaction vessel 19 containing a plurality ofcatalyst reaction beds 20, 21 and 22 having gas collection areas 23, 24and 25 spaced above and between the catalyst beds. The hydrocarbon-watermixture as an emulsion is fed into the first of the catalyst beds 20from line 26 to flood the catalyst bed and therein become partiallyconverted to gas product which is collected in the gas space 23 to beremoved through the outlet line 27. The unconverted liquid mixture isthen passed to the next catalyst bed 21 to be further partiallyconverted to gas product which collects in gas space 24 and is removedthrough outlet pipe 28. Again in bed 22, the emulsion passed thereto ispartially converted to form gas collected in space 25 and removedthrough line 29. Following each bed 20, 21 and 22, the emulsion ispassed into the gas disengaging chambers 30, 31 and 32. The movement ofthe unconverted emulsion may thus be repeated through a sequence ofcatalyst beds or reaction cites. Gas is removed by line 29 from gasspace 25 and residual liquid emulsion by line 33.

Any remaining unconverted hydrocarbon and water in liquid phase can berecycled to the first reaction bed. The product gases evolved orgenerated in each of the beds can be collected and separated into theircomponents by known methods which may employ fractional liquefaction,distillation, selective adsorption and/or selective absorption.

The gas outlet pipes may include a tube which permits preferentialescape of hydrogen from the gas product mixture such as palladium,palladium-silver or porous tetrafluoroethylene tube such tubes being inchambers from which the separated hydrogen can be withdrawn.

In the emulsion reactors shown in FIG. 1 and FIG. 2 a differentialreaction is achieved by having the catalyst submerged in the aqueoushydrocarbon oil emulsion and removing the product gas as it is generatedso that the product gas does not recontact the catalyst. Thus, ahydrogen-rich gas product may be constantly removed from the reactorwith low expenditure of energy for circulation of the liquid emulsion.By keeping the said hydrocarbon and water mainly in the liquid phase,the only thermal requirements of the system are the endothermic heat ofreaction with a relatively small amount of heat of vaporization.

The liquid phase reforming is carried out at sufiiciently lowtemperatures to keep the total gas and vapor pressures at a suitablelevel. As the pressure is increased, more product gas may tend to remaindissolved in the emulsion, but steps may be taken to further degasifythe emulsion. Allowing the vapor pressure of the hydrocarbon and of thewater to increase defeats the purpose of lowering the thermalrequirements. Thus, reasonable liquid reforming reactions are operatedat pressures in the range of 1 to atms. using higher pressures for themore volatile hydrocarbons.

If the liquid phase reforming or emulsion reactor is operated inconjunction with a hydrogen fuel cell, heat for the reforming reactioncan be supplied by heat transfer of excess heat in the electrochemicalsystem.

PREFERRED EMBODIMENTS Example 1 High activity, high nickel-contentcatalyst.A nickelalumina-lanthanum catalyst with a nickel to aluminumatom ratio of 3:1 was prepared as follows: 320 grams of Al(NO -9H O and750 grams of Ni(NO -6H O were added to 3 liters of deionized water andthe solution brought to 120 F. While stirring, 750 grams NH HCO wereadded over an approximate one-hour period while maintaining thetemperature at 120 F. After the precipitation was completed, the slurrywas stirred an additional hour at 120 F. and then filtered. To the wetcatalyst paste was added 93.6 grams of La(NO -6H O dissolved indeionized water and the mixture stirred well. The catalyst was driedovernight at 230 F. and then calcined in air for four hours at 750 F.

The calcined catalyst is activated for use as a reforming catalyst by areduction or treatment such as the flowing stream of hydrogen attemperatures of 600 to 900 F. for 1 or several hours. In this reductiontreatment, nickel oxide interspersed in the alumina is reduced tometallic nickel. Promoting metals, e.g., La, Ba, Sr, Ce, Cs, K, Fe, Y,Cu and mixtures thereof are considered to be present as oxides. Thesepromoting metals may be added to the dried nickel-alumina catalystbefore calcination by impregnating with decomposable compounds inaqueous solution such as nitrate salts of the promoting metals.

Example 2 Liquid phase reforming system batch perali0n.-To a glassreaction vessel at atmospheric pressure was charged 240 grams of anickel-alumina-lanthanurn catalyst prepared as in Example 1. Thecatalyst was then reduced by contacting it overnight with a solutioncontaining 200 grams of lithium biphenyl radical anion dissolved in 1000grams of tetrahydrofuran at room temperature. The radical anion solutionwas drained from the reactor and 250 cc.s of a freshly prepared emulsioncontaining 4 volumes of water per volume of decanc, prepared by use of anitrogen blanketed blender was passed under a hydrostatic pressure above1 atm. to the reactor. Care was taken to allow a gas separation zonefree of catalyst to remain above the emulsion-catalyst mixture so thatproduct gas could escape readily. Product gas was measured by a wet testmeter and gas samples were taken in stainless steel bombs for analysisby a mass spectrometer. After an initial line out period, gas flowedunder superatmospheric pressure from the reactor at 140 F. starting at arate of 0.5 liter per hour. Samples of the product gas on a dry basisanalyzed as follows:

TABLE Sample Run 1 Run 2 Mole Percent Hydrogen- 58.1 66.0 Methane gThese test runs demonstrated that the system was operative at lowtemperatures and under atmospheric pressures or above without need ofpumping using liquid hydrocarbons.

Example 3 emulsion flowing in sequence through the remaining beds ofcatalyst and the gas product evolved in each of the beds was removedinto a space above the beds and from there to outside the reactor tubeto be passed to a separator chamber where liquid was separated. Gas fromthe separator chamber was passed through a wet gas meter. Product gascontaining principally H and CO was removed at a steady rate after theemulsion was flowing through the reactor tube in a manner to flood eachof the beds of catalyst of not more than 4 cm. depth.

With a minimum of back mixing of gas product with catalyst, with thetemperature of reaction raised to 500 F. to obtain 0 up to 3% conversionof the decane per bed in the differential reactor, the gas product tendsto contain up to 76 mole percent H and 24 mole percent CO on a drybasis, based on the overall reaction:

With the hydrocarbon oil feed free of gaseous hydrocarbons, the liquidphase reforming produces a gas product containing typically 65 to molepercent H 18 to 29 mole percent CO less than 5 mole percent gaseoushydrocarbons which cannot be condensed at atmospheric temperatures, anda negligible amount of CO. Such a gas product can be economicallypurified to a H gas simply by removing CO I claim:

1. In a differential reaction process for producing hydrozen using anactive nickel-containing reforming catalyst that promotes reaction of ahydrocarbon oil with water to form H and CO said catalyst containing 10to 75 wt. percent nickel interspersed with an oxide of the groupconsisting of alumina and silica and having a nickel surface area of atleast 20 m. /g., the improvement which comprises:

contacting liquid hydrocarbon oil and water in liquid phase with thecatalyst at low reaction temperatures in the range of F. to 500 F. undersuper-atmospheric pressures to maintain said hydrocarbon oil and liquidin liquid phase while a portion of the hydrocarbon oil is converted togenerate hydrogen gas product containing H and CO and removing said gasproduct as it is generated to recover hydrogen.

2. The process of claim 1 wherein said catalyst is submerged in anaqueous emulsion of the hydrocarbon oil in water and said gas product isremoved as generated from the emulsion to a contiguous gas collectionzone free of said catalyst.

3. The process of claim 1 wherein said liquid hydrocarbon oil comprisesmainly paraffinic hydrocarbons containing at least 5 carbon atoms permolecule.

4. The process of claim 1 wherein said catalsyt contains 40 to 45 wt.percent nickel interspersed with alumina and 0.5 to 12 wt. percent of apromoter metal selected from the group consisting of La, Ba, Sr, Ce, Cs,K, Fe, Y and Cu and has a nickel surface area of 20 to 30 m. g.

References Cited UNITED STATES PATENTS Re. 19,733 10/1935 Hansgirg23-213 3,069,250 12/ 1962 Weittenhiller et al. 23-213 XR 3,147,0809/1964 Jahnig 23-212 3,320,182 5/1967 Taylor et al. 23-212 XR FOREIGNPATENTS 7,128 5/ 1927 Australia. 9,017 8/1927 Australia.

OSCAR R. VERTIZ, Primary Examiner. EDWARD STERN, Assistant Examiner.

